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SubjectRe: [PATCH v2 2/7] dt-bindings: interrupt-controller: apple,aic2: New binding for AICv2
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On 26/02/2022 05.19, Rob Herring wrote:
>> +properties:
>> + compatible:
>> + items:
>> + - const: apple,t6000-aic
>> + - const: apple,aic2
>
> I feel I was sold on Apple doesn't change h/w and we're the 2nd chip in
> and the h/w changed. Just my musings, but aic3 will be rejected. :(

Well yes, after not changing hardware for N phone/tablet generations,
they figured out they *finally* had to make some changes for real
desktop chips... (t8103 was a tablet chip they shoehorned into laptops;
t6000 is the first real laptop/desktop chip). This isn't the 2nd chip
in, this is the 26th chip in or so, and yet it's called AIC2 (by Apple
even)... We aren't starting from chip #1, just the first chip they
decided to *let* us put Linux on.

It's pretty clear that the t6000 changes were made with future-proofing
in mind. I guess we'll find out in a couple weeks, since the rumor mill
says M2 is coming. If I'm right and we end up needing *zero* kernel
changes to boot on M2, will you be happy? ;-)

>> + apple,event-reg:
>> + $ref: /schemas/types.yaml#/definitions/uint32
>> + description:
>> + Specifies the offset of the event register, which lies after all the
>> + implemented die register sets, page aligned. This is not computable from
>> + capability register values, so we have to specify it explicitly.
>
> If this is last, then couldn't it be a 2nd 'reg' entry?
>
> 'page aligned' is ambiguous. I assume that means 16K since that's what
> Apple uses, but I might assume 4K not knowing that.

16K, and yeah, it could be a 2nd reg entry if you think that works
better. Makes sense.

--
Hector Martin (marcan@marcan.st)
Public Key: https://mrcn.st/pub

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